If I have the Rockstar Games launcher running, I will receive an error when I try to launch Opera Portable, saying that it is already running. If I close the Rockstar Launcher, I can then open Opera Portable. If I open Opera first, I can then open the Rockstar Launcher without any conflicts after that as long as I don't close and reopen Opera.
Does this mean the Rockstar Launcher is built upon Opera Portable? Or maybe just regular Opera? It's kinda weird, whatever the cause!